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- /* Common Linux native ptrace code for AArch64 MTE.
- Copyright (C) 2021-2022 Free Software Foundation, Inc.
- This file is part of GDB.
- This program is free software; you can redistribute it and/or modify
- it under the terms of the GNU General Public License as published by
- the Free Software Foundation; either version 3 of the License, or
- (at your option) any later version.
- This program is distributed in the hope that it will be useful,
- but WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- GNU General Public License for more details.
- You should have received a copy of the GNU General Public License
- along with this program. If not, see <http://www.gnu.org/licenses/>. */
- #include "gdbsupport/common-defs.h"
- #include "gdbsupport/byte-vector.h"
- #include "linux-ptrace.h"
- #include "arch/aarch64.h"
- #include "arch/aarch64-mte-linux.h"
- #include "nat/aarch64-linux.h"
- #include "nat/aarch64-mte-linux-ptrace.h"
- #include <sys/uio.h>
- /* Helper function to display various possible errors when reading
- MTE tags. */
- static void ATTRIBUTE_NORETURN
- aarch64_mte_linux_peek_error (int error)
- {
- switch (error)
- {
- case EIO:
- perror_with_name (_("PEEKMTETAGS not supported"));
- break;
- case EFAULT:
- perror_with_name (_("Couldn't fetch allocation tags"));
- break;
- case EOPNOTSUPP:
- perror_with_name (_("PROT_MTE not enabled for requested address"));
- default:
- perror_with_name (_("Unknown MTE error"));
- break;
- }
- }
- /* Helper function to display various possible errors when writing
- MTE tags. */
- static void ATTRIBUTE_NORETURN
- aarch64_mte_linux_poke_error (int error)
- {
- switch (error)
- {
- case EIO:
- perror_with_name (_("POKEMTETAGS not supported"));
- break;
- case EFAULT:
- perror_with_name (_("Couldn't store allocation tags"));
- break;
- case EOPNOTSUPP:
- perror_with_name (_("PROT_MTE not enabled for requested address"));
- default:
- perror_with_name (_("Unknown MTE error"));
- break;
- }
- }
- /* Helper to prepare a vector of tags to be passed on to the kernel. The
- main purpose of this function is to optimize the number of calls to
- ptrace if we're writing too many tags at once, like a pattern fill
- request.
- Return a vector of tags of up to MAX_SIZE size, containing the tags that
- must be passed on to the kernel, extracted from TAGS, starting at POS.
- GRANULES is the number of tag granules to be modified. */
- static gdb::byte_vector
- prepare_tag_vector (size_t granules, const gdb::byte_vector &tags, size_t pos,
- size_t max_size)
- {
- gdb::byte_vector t;
- if (granules == 0)
- return t;
- gdb_assert (tags.size () > 0 && max_size > 0);
- if (granules > AARCH64_MTE_TAGS_MAX_SIZE)
- t.resize (AARCH64_MTE_TAGS_MAX_SIZE);
- else
- t.resize (granules);
- size_t tag_count = tags.size ();
- for (size_t i = 0; i < t.size (); i++)
- t[i] = tags[(pos + i) % tag_count];
- return t;
- }
- /* See nat/aarch64-mte-linux-ptrace.h */
- bool
- aarch64_mte_fetch_memtags (int tid, CORE_ADDR address, size_t len,
- gdb::byte_vector &tags)
- {
- size_t ntags = aarch64_mte_get_tag_granules (address, len,
- AARCH64_MTE_GRANULE_SIZE);
- /* If the memory range contains no tags, nothing left to do. */
- if (ntags == 0)
- return true;
- gdb_byte tagbuf[ntags];
- struct iovec iovec;
- iovec.iov_base = tagbuf;
- iovec.iov_len = ntags;
- tags.clear ();
- bool done_reading = false;
- /* The kernel may return less tags than we requested. Loop until we've read
- all the requested tags or until we get an error. */
- while (!done_reading)
- {
- /* Attempt to read ntags allocation tags from the kernel. */
- if (ptrace (PTRACE_PEEKMTETAGS, tid, address, &iovec) < 0)
- aarch64_mte_linux_peek_error (errno);
- /* Make sure the kernel returned at least one tag. */
- if (iovec.iov_len <= 0)
- {
- tags.clear ();
- return false;
- }
- /* Copy the tags the kernel returned. */
- for (size_t i = 0; i < iovec.iov_len; i++)
- tags.push_back (tagbuf[i]);
- /* Are we done reading tags? */
- if (tags.size () == ntags)
- done_reading = true;
- else
- {
- address += iovec.iov_len * AARCH64_MTE_GRANULE_SIZE;
- iovec.iov_len = ntags - iovec.iov_len;
- }
- }
- return true;
- }
- /* See nat/aarch64-mte-linux-ptrace.h */
- bool
- aarch64_mte_store_memtags (int tid, CORE_ADDR address, size_t len,
- const gdb::byte_vector &tags)
- {
- if (tags.size () == 0)
- return true;
- /* Get the number of tags we need to write. */
- size_t ntags = aarch64_mte_get_tag_granules (address, len,
- AARCH64_MTE_GRANULE_SIZE);
- /* If the memory range contains no tags, nothing left to do. */
- if (ntags == 0)
- return true;
- bool done_writing = false;
- size_t tags_written = 0;
- /* Write all the tags, AARCH64_MTE_TAGS_MAX_SIZE blocks at a time. */
- while (!done_writing)
- {
- gdb::byte_vector t = prepare_tag_vector (ntags - tags_written, tags,
- tags_written,
- AARCH64_MTE_TAGS_MAX_SIZE);
- struct iovec iovec;
- iovec.iov_base = t.data ();
- iovec.iov_len = t.size ();
- /* Request the kernel to update the allocation tags. */
- if (ptrace (PTRACE_POKEMTETAGS, tid, address, &iovec) < 0)
- aarch64_mte_linux_poke_error (errno);
- /* Make sure the kernel wrote at least one tag. */
- if (iovec.iov_len <= 0)
- return false;
- tags_written += iovec.iov_len;
- /* Are we done writing tags? */
- if (tags_written == ntags)
- done_writing = true;
- else
- address += iovec.iov_len * AARCH64_MTE_GRANULE_SIZE;
- }
- return true;
- }
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